Customer:
I purchased 4N35 optocouplers from you previously. Now I need advice on what resistor value to put in series with 3 4N35 optocouplers connected in series. The supply voltage is 12V.
Original message (Croatian)
Kod vas sam svojevremeno kupio optocouplere 4N35 . Sada mi je aktuelno , pa bih vas zamolio za savjet koju vrijednost otpornika metnuti u seriju sa 3 optocouplera 4N35 serijski vezana? Napajanje je 12V.
hvala i Lp
Originally submitted via email support on 16 January 2023. Migrated to the forum for community visibility.
Soldered Support:
Could you explain what the purpose is of connecting the optocouplers in series?
The resistor for the LED is calculated using Ohm’s law. It is important that the current through the LED does not exceed 10mA. You can use this calculator for calculating the resistor value: https://www.digikey.com/en/resources/conversion-calculators/conversion-calculator-led-series-resistor
Original message (Croatian)
mogu li Vas zamoliti da mi objasnite koja je svrha spajanja optocouplera u seriju?
Otpornik za LED se računa preko Ohmovog zakona. Bitno je da struja kroz LED ne bude veća od 10mA. Možete koristiti čak i ovaj kalkulator za računanje vrijednosti otpornika https://www.digikey.com/en/resources/conversion-calculators/conversion-calculator-led-series-resistor.
Customer:
Thank you for the response. However, I am still unclear about the supply voltage of the 4N35 optocoupler. I am connecting them in series (3 units) to function as a power supply switch for three instruments, and they are powered by 9V batteries. The idea is that when the device is not turned on, the instruments do not drain the batteries. It would help me if you could calculate the resistor value/W that I should connect in series with the optocouplers.
Original message (Croatian)
Hvala na odgovoru. Međutim nejasan mi je i napon napajanja predmetnog optocouplera (4N35). Vežem ih u seriju (3kom.) da mi vrše funkciju uspostave i prekida napajanja tri instrumenta, a napajaju se sa baterijama od 9V. Naime hoću da kada uređaj nije uključen instrumenti ne troše baterije. Pomoglo bi mi ako možete, da mi samo izračunate vrijednos otpornika/W koji ću vezati u seriju sa optocouplerima Hvala i pozdrav, Tom Poslano iz programa Pošta za Windows Pošiljatelj: [name removed] ([name removed])
Poslano:18. siječnja 2023. 8:46
Primatelj: [name removed]
Soldered Support:
Unfortunately I cannot calculate the resistor you need as that would go beyond customer support into project development. However, I can guide you on how to solve your problem.
As you can see in the technical documentation, the voltage at which the diode starts to work is 1.3 V (Forward voltage). Using the calculator I sent you in the previous message, you can calculate which resistor you need. You need to enter the supply voltage (battery or similar), the forward voltage (from the technical documentation), and the desired current through the LED. Do not set the current higher than 10mA.
Original message (Croatian)
nažalost ne mogu Vam izračunati otpornik koji Vam treba jer bi to prešlo u razvoj projekta što mi kao korisnička podrška ne radimo. Nadam se da razumijete ovo, no mogu Vas uputiti kako da riješite svoj problem.
Kao što vidite u tehničkoj dokumentaciji napon pri kojem dioda krene raditi je 1.3 V (Forward voltage), te onda pomoću kalkulatora kojeg sam Vam poslao u prethodnoj poruci možete izračunati koji Vam otpornik treba. Potrebno je unjeti napon napajanja (baterija ili slično), forward voltage (ovaj iz tehničke dokumentacije) i željenu struju kroz LED. Struju nemojte stavljati više od 10mA.
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